The present invention relates to devices and methods for reducing injury in some types of vehicle/pedestrian collisions. More particularly, the present invention pertains to methods and devices that mitigate pre-contact and post-contact injuries arising from some types of vehicle/pedestrian collisions such as traumatic brain injuries.
Many devices have been proposed to reduce the incidence of impact resultant head injuries in collisions between vehicles and pedestrians. Among them are various pop-up hood assemblies.
Impact resultant head injuries have been modeled and characterized using analysis based upon “Head Injury Criterion” (HIC) value. Various safety devices have been developed based on tests directed to and derived from head injury criterion value. The potential severity of traumatic brain injury (TBI) resulting from pedestrian-vehicle collisions is assessed by the HIC value obtained from the regulatory impactor test in which a free flight head form (human head size) is propelled to impact against a stationary vehicle to replicate head injury accidents involving pedestrians.
Head injury criterion (HIC) is a measure of the likelihood of head injury arising from an impact. It is defined as:
      H    ⁢                  ⁢    I    ⁢                  ⁢    C    =            {                                    [                                          1                                                      t                    2                                    -                                      t                    1                                                              ⁢                                                ∫                                      t                    1                                                        t                    2                                                  ⁢                                  a                  ⁢                                      ⅆ                    t                                                                        ]                    2.5                ⁢                  (                                    t              2                        -                          t              1                                )                    }        max  when t1, and t2 are initial and final times (in seconds) of the interval during which HIC attains maximum value and “a” is gravitational acceleration applied to the head. Typically, the maximum time duration (t2−t1) is limited to a specific value such as 36 ms for example, with t2−t1 generally being less than or equal to 15 ms.
While head injury criterion is a valuable tool for modeling the nature and severity of certain types of head impact injuries, an entire profile of serious injuries can arise as a result of pedestrian vehicle collisions that may not be encompassed or adequately evaluated by head injury criteria. Traumatic brain injury (TBI) can be closely associated with non-impact traction force due to inertia loading prior to head strike with a striking vehicle.
Thus, it may be desirable to provide an active hood lift method, system, and device for use with automotive vehicles that can protect pedestrians from at least a portion of the impact modes found to result in injuries.